1. Do you have specs listed anywhere for the rifled barrels?
2. Do the one piece barrels have the same bore size at the breech as they do at the muzzle? In other words, do they taper along their length and if so, are they the same?
3. The two piece test is rather interesting. There doesn't appear to be a trend amongst the different length barrel fronts. Was there porting on the fronts?
4. What was being tested with the Dye barrels that wasn't covered in the 12" various bores? Is the barrel different?

People have generally recommended 12-14" for a barrel length and its really cool to actually see some numbers to back that up. Looks like they were pretty close.

The 12" front/various back is really interesting. It seems that the paint to barrel match (see top note for paint size) in that instance showed the best efficiency. That's actually opposite of previous bore tests. Any ideas why that may be? Are the freak and CCM kits you guys used in the other tests different from the CP kit?

1. Do you have specs listed anywhere for the rifled barrels?2. Do the one piece barrels have the same bore size at the breech as they do at the muzzle? In other words, do they taper along their length and if so, are they the same?3. The two piece test is rather interesting. There doesn't appear to be a trend amongst the different length barrel fronts. Was there porting on the fronts?4. What was being tested with the Dye barrels that wasn't covered in the 12" various bores? Is the barrel different?

People have generally recommended 12-14" for a barrel length and its really cool to actually see some numbers to back that up. Looks like they were pretty close.

The 12" front/various back is really interesting. It seems that the paint to barrel match (see top note for paint size) in that instance showed the best efficiency. That's actually opposite of previous bore tests. Any ideas why that may be? Are the freak and CCM kits you guys used in the other tests different from the CP kit?

1. Nope, based on the mean velocity we assume they're huge. We tried to measure - but with the rifling it's really hard. Gordon got... I think .689 - but that would most likely be the "peaks" of the rifling.2. yes - same diameter throughout.3. yes, check CP's website for a picture - I don't have any. The two piece barrels have two extra rows of porting - otherwise all CP barrels were very similar in porting.4. Just to throw something else at very similar bore into the test.

As to your last point - we think it's because of how small paint tends to be. Since CP makes a .682 at the smallest we don't feel that we were able to actually underbore all that much.

In many cases the first shot is 20 or more FPS higher than subsequent shots. Do you have creep in the gun?

This test might benefit from two or three clearing shots before beginning to take measurements. At the very least, remove those outliers from the calculations of Mean and SD.

That's the beauty of standard deviation. Outliers won't affect the SD as much as it would say mean or range. Picking and choosing which shots to include or exclude isn't a good idea. That can get you into all sorts of problems. Its better to just include all data and analyze it from there. Besides, the bell curve will always have outliers towards the extrema.

That being said, a few clearing shots might be a good precautionary measure. Especially if there are asymptomatic problems with a gun.

Sorry, forgot to note - we knew going in that gordon's emag shoots hot on the first shot after sitting for a while. We wanted a sample size of 20 - so sampled 20 then removed high and low - leaving 20 data points per barrel.

Odin - I'm sure that's why you got different means - the first shot would certainly push the data sets up a few fps.

the first shot being hot is standard on gordon's emag - not on any other gun we've tested with. I don't know why - I assume that the valve reg has a little leak allowing the dump chamber to slightly creep up as the gun sits without venting the chamber. one shot and it's back on line - which is why we chose to take 22 samples and dump the high and low.

dropping the top and bottom value in a set is common practice to remove the outliers.

it works perfectly in this case, we recorded 22 values with each, drop the fastest and slowest, and still have a data set of 20 values.

i am also a bit disappointed to see that we couldn't get a very good underbore going. an odd thing to point out is that in our last test the "matched" did the worst, or worse then over boring anyway, and this test shows the opposite.

me and bryce have a theory as to why, we think.

The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

Sorry, forgot to note - we knew going in that gordon's emag shoots hot on the first shot after sitting for a while. We wanted a sample size of 20 - so sampled 20 then removed high and low - leaving 20 data points per barrel.

Odin - I'm sure that's why you got different means - the first shot would certainly push the data sets up a few fps.

Ahh, that would explain the difference in numbers I was seeing. Thanks for clearing that up.

the first shot being hot is standard on gordon's emag - not on any other gun we've tested with. I don't know why - I assume that the valve reg has a little leak allowing the dump chamber to slightly creep up as the gun sits without venting the chamber. one shot and it's back on line - which is why we chose to take 22 samples and dump the high and low.

I guess if you really wanted to, you could do an outlier Q test, but dropping one high and one low is an acceptable amount of data massaging.

Images used in signatures are to be less than Width of 600px, and height of 160px. Only ONE image is allowed in the signature, and it must be 30k or less. Only 5 lines of text are allowed. No text larger then size 2 is allowed in the signature

So, looking at the results, I (who suck at statistics) would conclude:

1. Tighter bore = higher velocities.

2. For one-piece barrels, 14" is the ideal length.

3. For two-piece barrels, the length of the tip matters a little, but anything from 10-16" is going to perform about the same. Yeah, they varied, but the differences were all pretty much within the standard deviation. With things that close, personal preference (ergonomics) is probably more important when actually playing paintball.

Any ETA for the results of your accuracy tests? I'm planning to buy a new barrel based on the final results of these tests, and I was hoping to have that show up on my December budget instead of January.

EDIT: Bryce, I just saw your response about the sorting. That makes a lot of sense.

Since these tests are using velocity change as the measured variable, shouldn't a marker that doesn't have velocity issues be used? Maybe an Ion with max dwell?

I'm assuming the main point of the barrel length tests was to determine if barrel length effected consistency? Each marker has a barrel length that is most efficient for its setup. Might want to put a disclaimer here so no one thinks a 14" barrel is most efficient on their gun... unless they have the same exact Emag setup.

Did all barrels have the same exact porting? What was the distance from the barrel tip to the start of the porting?

Was paint to barrel match .683?

Adjusting for the mag's shoot-up, it looks like length had a negligible effect on velocity consistency.

Since these tests are using velocity change as the measured variable, shouldn't a marker that doesn't have velocity issues be used? Maybe an Ion with max dwell?

I'm assuming the main point of the barrel length tests was to determine if barrel length effected consistency? Each marker has a barrel length that is most efficient for its setup. Might want to put a disclaimer here so no one thinks a 14" barrel is most efficient on their gun... unless they have the same exact Emag setup.

Did all barrels have the same exact porting? What was the distance from the barrel tip to the start of the porting?

Was paint to barrel match .683?

Adjusting for the mag's shoot-up, it looks like length had a negligible effect on velocity consistency.

answers to most of these have been posted - read a few posts up.

paint to barrel match was pretty small - depending on the ball somewhere around .685. So, in this test we were not able to achieve the level of underbore we did in previous tests. That said, the bore portion of this test pretty much lined up with what we got last time. The new analisys available with this test is the length and one v two piece design.

Based on this testing - I DO think that a 14" small bore barrel will be the most efficient on any gun.

The emag we used on this test achieved a SD of under 2 fps on previous tests with a sample size of 20 - it's a fantastic, consistent shooting gun - and as I posted above - the reason the data is in ascending order is that I sorted it that way to knock off the highest and lowest.

In the results I'm confused and don't really understand what the numbers on the graphs that are on they left mean can someone help me out? thanks

The signature in this location has been removed due to FORUM RULES VIOLATIONS. Please check this link : FORUM RULES AND REGS and feel free to repost your signature according to the guidelines set by this forum.

In the results I'm confused and don't really understand what the numbers on the graphs that are on they left mean can someone help me out? thanks

the two numbers that we're looking at for this test are:

mean velocity

and

SD (standard deviation)

mean velocity is a number that tells you how fast the ball was leaving the barrel. A higher mean velocity indicates that with the gun set the same - that barrel is going to shoot faster. This indicates that you could get more shots at a specific velocity from the same tank out of a barrel with a higher mean velocity.

Standard Deviation (SD) is an indication of how consistent that barrel is. the lower the number the more consistent. A low SD will directly correlate to having a lower +/- fps when chronoing a gun. Additionally, it's my assumption that a more consistent gun will be a more accurate one.

It might also be worth noting the porting when referring to a barrel length as 'most efficient'. Wouldn't you have to test more then one gun to make that claim though? Try just shooting the emag with a higher or lower internal pressure and I'll bet you get a different 'most efficient' length. Maybe do a string of 'hot' shots by pausing between shots so the dump chamber can reach ambient.

The emag might be consistent with one type of barrel and paint, but as shown in the "dry fire vs paint efficiency test" backpressure can effect it's operation for better or worse.

It might also be worth noting the porting when referring to a barrel length as 'most efficient'. Wouldn't you have to test more then one gun to make that claim though? Try just shooting the emag with a higher or lower internal pressure and I'll bet you get a different 'most efficient' length. Maybe do a string of 'hot' shots by pausing between shots so the dump chamber can reach ambient.

The emag might be consistent with one type of barrel and paint, but as shown in the "dry fire vs paint efficiency test" backpressure can effect it's operation for better or worse.

Thanks for noting the sorting. That was really throwing me off.

if the goal however is pure shot to shot consistency that gun is so far the best gun i have ever seen in my 9 years now of playing paintball. it is simply amazing over the chrono. seriously, i have seen and shot them all, from AKA to DM and such, and that emag is amazing over the chrono. it is unquestionably the most consistent gun i have ever laid hands on. it beats my cyborg by at least 50%. the dry fire vs with paint does little in comparison to shot to shot consistency, that is a test that deals primarily with the pressure in the dump chamber when cycling normally, which, as long as the gun shoots consistent doesn't matter one bit.

would it have been easier that we simply shoot 3 times before each test and not record it? to me, it makes alot more sense to have a standard procedure like droping the high and low, a STANDARD manipulation of data widely accepted in experimental dings.

porting and length of back are factors, i'd agree there. the CP backs looked to me to be 4 or 5 inches long, but we can see the effect of 12, 14, and 16 inch "control bores" with the one piece test.

Edited by cockerpunk, 29 December 2008 - 11:47 PM.

The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

It might also be worth noting the porting when referring to a barrel length as 'most efficient'. Wouldn't you have to test more then one gun to make that claim though? Try just shooting the emag with a higher or lower internal pressure and I'll bet you get a different 'most efficient' length. Maybe do a string of 'hot' shots by pausing between shots so the dump chamber can reach ambient.

The emag might be consistent with one type of barrel and paint, but as shown in the "dry fire vs paint efficiency test" backpressure can effect it's operation for better or worse.

Thanks for noting the sorting. That was really throwing me off.

No, we don't have to test more than one gun to make the efficiency claim. A gun is a valve - how that valve gets air into the barrel is WAY less important than how the air interacts as the ball is accellerating.

I do see what you're getting at - maybe a steep slope on the power pulse would result in a shorter optimal barrel length? Maybe. However, the way a gun delivers air isn't going to radically effect optimal barrel length. On the Emag it's 14" Maybe we'll shoot the Cyborg on Friday and test 10, 12, 14, 16 again. Wouldn't take long - but I'm willing to lay money on the same results. Whatever the gun's power pulse looks like the ball is going from 0 fps to 300 fps in a very, very short time - and the distances that it takes to get to that speed are going to be very similar on all guns.

sorry about the sorting - I should have noted that from the begining

For more accurate 1-piece vs 2-piece comparsion, shouldn't you test with .685 back?

It might also be worth noting the porting when referring to a barrel length as 'most efficient'. Wouldn't you have to test more then one gun to make that claim though? Try just shooting the emag with a higher or lower internal pressure and I'll bet you get a different 'most efficient' length. Maybe do a string of 'hot' shots by pausing between shots so the dump chamber can reach ambient.

The emag might be consistent with one type of barrel and paint, but as shown in the "dry fire vs paint efficiency test" backpressure can effect it's operation for better or worse.

Thanks for noting the sorting. That was really throwing me off.

No, we don't have to test more than one gun to make the efficiency claim. A gun is a valve - how that valve gets air into the barrel is WAY less important than how the air interacts as the ball is accellerating.

I do see what you're getting at - maybe a steep slope on the power pulse would result in a shorter optimal barrel length? Maybe. However, the way a gun delivers air isn't going to radically effect optimal barrel length. On the Emag it's 14" Maybe we'll shoot the Cyborg on Friday and test 10, 12, 14, 16 again. Wouldn't take long - but I'm willing to lay money on the same results. Whatever the gun's power pulse looks like the ball is going from 0 fps to 300 fps in a very, very short time - and the distances that it takes to get to that speed are going to be very similar on all guns.

sorry about the sorting - I should have noted that from the begining

Hmmm. Shouldn't an LP gun require a longer barrel than an HP gun? After all, its using less pressure but requires more volume. Wouldn't that necessitate a longer barrel to accelerate the ball up to field velocity? I would think that an HP gun accelerates the ball in a shorter distance and wouldn't require as long of a barrel. If that's true, perhaps you should repeat the test with an opposite pressure gun. I don't know if the Emag is HP or LP. Or do you think that the barrel length difference is negligible?

Those differences mostly get washed out in the valving, before the ball sees them. What we're really concerned with is the 'shape' of the power pulse that hits the ball - acceleration is part of this shape and the pressure tends to build much faster than the ball is accelerated - I would tend to disagree with bryce that the length will be totally independent of gun - think about it:

For a given efficiency gun, you need X amount of pressure*volume work to get to field velocity.

The point at which you get diminishing returns on the barrel length is where the pressure*area of a paintball is less than drag + friction. Generally this will occur at a given system volume, where the system is barrel + dump chamber+ pre-expansion volume. Note that for poppet guns or anything sealing the chamber, the dynamics get even more complicated and must be modeled in at least 2 steps.

so, do you think thats a large enough effect to notice? like measure in inches?

idk, i see theoretically where you are going, but i just dont think it will have a very large effect.

i would expect the porting pattern and whatnot to have a larger effect, for example. we saw that there was similarities with the dye barrels compared to the CP ones, even though they are ported and built differently. at the same time we saw some slight differences.

The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

and you need, say, 115 in-lbs to fire the ball...that means a 150psi gun's dump chamber is what, 1 inch cubic, perhaps? I feel like that puts about a 3 inch cap as far as variance on the whole thing. I think it's probably one of those things that you could confirm with the right experiment, but it might now fall out naturally of others...Meaning as far as scale goes, we don't really care.

Hmmm. Shouldn't an LP gun require a longer barrel than an HP gun? After all, its using less pressure but requires more volume. Wouldn't that necessitate a longer barrel to accelerate the ball up to field velocity? I would think that an HP gun accelerates the ball in a shorter distance and wouldn't require as long of a barrel. If that's true, perhaps you should repeat the test with an opposite pressure gun. I don't know if the Emag is HP or LP. Or do you think that the barrel length difference is negligible?

the emag is HP - BUT, and this is a big but, operating pressure has very little to do with breech pressure. Breech pressure is more dependent on valve design.

We could certainly put a LP spoolie up against a HP poppet and see if barrel length changes. That would be an easy basement test. dunno if we'll have time to add it to Friday - we're already going to be busy.

In many cases the first shot is 20 or more FPS higher than subsequent shots. Do you have creep in the gun?

This test might benefit from two or three clearing shots before beginning to take measurements. At the very least, remove those outliers from the calculations of Mean and SD.

That's the beauty of standard deviation. Outliers won't affect the SD as much as it would say mean or range. Picking and choosing which shots to include or exclude isn't a good idea. That can get you into all sorts of problems. Its better to just include all data and analyze it from there. Besides, the bell curve will always have outliers towards the extrema.

That being said, a few clearing shots might be a good precautionary measure. Especially if there are asymptomatic problems with a gun.

I would second that discarding outliers is problematic for validity, but using a certain number of clearing shots as a pretest operation would be a methodologically sound idea.

In the results I'm confused and don't really understand what the numbers on the graphs that are on they left mean can someone help me out? thanks

the two numbers that we're looking at for this test are:

mean velocity

and

SD (standard deviation)

mean velocity is a number that tells you how fast the ball was leaving the barrel. A higher mean velocity indicates that with the gun set the same - that barrel is going to shoot faster. This indicates that you could get more shots at a specific velocity from the same tank out of a barrel with a higher mean velocity.

Standard Deviation (SD) is an indication of how consistent that barrel is. the lower the number the more consistent. A low SD will directly correlate to having a lower +/- fps when chronoing a gun. Additionally, it's my assumption that a more consistent gun will be a more accurate one.

does that help?

yes thank you very much great job with your test very well put together thanks again

The signature in this location has been removed due to FORUM RULES VIOLATIONS. Please check this link : FORUM RULES AND REGS and feel free to repost your signature according to the guidelines set by this forum.

...Standard Deviation (SD) is an indication of how consistent that barrel is. the lower the number the more consistent. A low SD will directly correlate to having a lower +/- fps when chronoing a gun. Additionally, it's my assumption that a more consistent gun will be a more accurate one....

I realize it's a lot to ask, but will the individual velocity and impact location of each ball be charted during accuracy tests? Would be interesting to see how much accuracy is effected by velocity fluctuations. Maybe that's one for another test?

Since the gun is going to be clamped down, I don't see why it couldn't be chrono'd as well. To see if there is a direct correlation, it would be suggested to record the velocity and its hit location together. I wouldn't separate those two values through sorting or exclusion as they may be linked.

Since the gun is going to be clamped down, I don't see why it couldn't be chrono'd as well. To see if there is a direct correlation, it would be suggested to record the velocity and its hit location together. I wouldn't separate those two values through sorting or exclusion as they may be linked.

Especially if you have an estimate for what the drop should be based on velocity - use the excellent paintball trajectory calculator for that. That way, each shot can be normed to it's own zero - interesting when you're only investigating, say, the effect a barrel has, independent of gun.

It's a pain to send one man downrange while the other shoots, but damn...it would be interesting.

we will be re-chonoing the gun in the XY grid test. i dont know if we will chrono each shot in that test, we have alot to do that day, so we might just make sure they are all shooting in a certain range before testing.

Edited by cockerpunk, 31 December 2008 - 11:25 AM.

The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

we will be re-chonoing the gun in the XY grid test. i dont know if we will chrono each shot in that test, we have alot to do that day, so we might just make sure they are all shooting in a certain range before testing.